This invention relates to a continuous power systems which provide standby power to computers, telecommunications equipment, process controllers and like equipment where uninterrupted power is requisite for reliable operation. In particular, the invention relates to a bi-directional AC to DC and DC to AC converter for use in a continuous power system.
One type of common continuous power system comprises a DC power storage device, or battery, coupled to a DC to AC converter which can be coupled to AC load terminals through a switch whenever AC mains power fails. AC mains power is normally coupled to AC load terminals when the continuous power system is in a standby condition. The continuous power system generally includes a separate charging subsystem in order to maintain the DC power storage device in readiness. Such charging subsystems add weight and cost to the continuous power system, and they are typically of relatively low recharge capacity. Consequently, a considerable amount of time is required to bring a discharged DC power storage device back to full readiness. A second type of continuous power system includes both an AC to DC converter and a DC to AC converter and a battery floating near the DC potential. All components are essentially operating at all times, and the capacity of the AC to DC converter must be comparable to the capacity of the DC to AC converter. Such systems are expensive and heavy.
A concern with known continuous power systems is the adverse effects of reactive loads on system operation. Reactive loads have been known to cause instabilities which result in poor performance and can cause system failure. There is a need for a lightweight continuous power supply which is capable of efficiently driving reactive loads yet which is capable of rapid recharge. A particular application of such a system would be in portable operation.